Study of transient quantum phases of matter via light-control of dynamical charge correlations

通过动态电荷关联的光控制研究物质的瞬态量子相

• 批准号: 571425-2021
• 负责人: Boschini, Fabio
• 金额: $ 3.28万
• 依托单位: Institut national de la recherche scientifique
• 依托单位国家: 加拿大
• 项目类别: Alliance Grants
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=729159
• 关键词: Study; transient; quantum; phases; matter

We often identify quantum materials as solid systems wherein strong electron interactions, in concert with low-dimensionality, lead to the emergence of phenomena unexplainable via (quasi-)classical approaches, such as superconductivity, and charge order. The scientific community has extensively studied the ground state of quantum materials in the past decades, but only very recently have we begun to develop tools for controlling the properties of materials on demand. In this regard, light-matter interaction is probably the most powerful and flexible tuning knob to control the properties of solids. Recent proof of principle demonstrations of this approach span light-induced superconductivity to photoinduced metal-to-insulator transitions.Charge order, i.e. the self-reorganization of the electronic density, is a common feature among quantum materials, and it may assume different forms ranging from long-range domains to short-range and dynamical (fluctuating) charge correlations. The later are of renewed interest as they are believed to be a fundamental ingredient (hidden until very recently) for understanding some of the technological-relevant properties of quantum materials such as superconductivity, nematicity and linear resistivity. This multi-institutional collaboration across Canada connecting INRS (Boschini), McGill University (Siwick) and QMI-UBC (Damascelli and Berciu), as well as other national and international collaborators, propose to use high-intense ultrashort light excitations (in the visible to THz range) to control the strength and spatial distribution of dynamical charge correlations in a variety of quantum materials. The importance of this project is backed by the idea that dynamical charge correlations could be a general feature of all quantum materials, arising from the specific spatial dependence of the electron interactions inside solids. In fact, while the interaction among two electrons in free space decays monotonically with distance (the well-known Coulomb's law), the electron-localization and lattice periodicity of solids may result in an effective non-monotonic Coulomb potential which may favour electron pairing and correlations. The use of light pulses precisely tailored to specific systems' energetics will allow us to transiently change the lattice structure along specific crystallographic directions, as well as tune the on-site electron-electron screening to lock or dissolve dynamical charge correlations in an ultrafast fashion. Not only will this study offer brand-new information on the microscopic origin of dynamical charge correlations in solids, but it will establish the light-control of dynamical charge correlations as a new, generalizable approach to tune the properties of quantum matter on demand.This ambitious project will be made possible by the unique opportunity of combining complementary ultrafast techniques, such as time-resolved photoemission spectroscopy (TR-ARPES - using the two systems of Boschini and Damascelli with different working parameters), ultrafast electron diffuse scattering (UEDS - Siwick), and free-electron-laser-based x-ray scattering (TR-XRS - Boschini). While TR-ARPES accesses fundamental electrodynamics with momentum resolution, UEDS and TR-XRS map the transient evolution of the phonon populations and lattice reconstructions. In addition, theoretical support (Berciu) will be essential to guide the interpretation of experimental data. Not only this project will grant an unprecedented peek into the dynamical properties of quantum materials, but will train highly qualified personnel in ultrafast science across Canada.

我们通常将量子材料视为固体系统，其中强电子相互作用与低维性相结合，导致出现无法通过（准）经典方法解释的现象，例如超导性和电荷序。在过去的几十年里，科学界已经广泛研究了量子材料的基态，但直到最近，我们才开始开发根据需要控制材料特性的工具。在这方面，光-物质相互作用可能是控制固体性质的最强大和最灵活的调节旋钮。电荷有序，即电子密度的自重组，是量子材料的一个共同特征，它可以呈现不同的形式，从长程畴到短程和动态（波动）电荷关联。后者重新引起了人们的兴趣，因为它们被认为是理解量子材料的一些技术相关性质的基本成分（直到最近才被发现），如超导性，向列性和线性电阻率。 这种跨加拿大的多机构合作连接INRS（Boschini），麦吉尔大学（Siwick）和QMI-UBC（Damascelli和Berciu）以及其他国家和国际合作者，建议使用高强度超短光激发（在可见光到THz范围内）来控制各种量子材料中动态电荷相关性的强度和空间分布。该项目的重要性得到了以下想法的支持：动态电荷相关性可能是所有量子材料的一般特征，源于固体内部电子相互作用的特定空间依赖性。事实上，虽然自由空间中两个电子之间的相互作用随距离单调衰减（众所周知的库仑定律），但固体的电子局域化和晶格周期性可能导致有效的非单调库仑势，这可能有利于电子配对和相关性。使用针对特定系统的能量学精确定制的光脉冲将使我们能够沿着特定的晶体学方向瞬时改变晶格结构，并调整现场电子-电子屏蔽，以超快方式锁定或溶解动态电荷相关性。这项研究不仅将提供有关固体中动态电荷相关性微观起源的全新信息，而且将建立动态电荷相关性的光控，作为一种新的、可推广的方法，按需调节量子物质的性质。这个雄心勃勃的项目将通过结合互补超快技术的独特机会而成为可能，例如时间分辨光电子能谱（TR-ARPES -使用具有不同工作参数的Boschini和Damascelli两个系统）、超快电子漫散射（UEDS-Siwick）和基于自由电子激光的X射线散射（TR-XRS - Boschini）。虽然TR-ARPES访问基本电动力学与动量分辨率，UEDS和TR-XRS映射声子种群和晶格重建的瞬态演化。此外，理论支持（Berciu）将是必不可少的，以指导实验数据的解释。该项目不仅将为量子材料的动力学特性提供前所未有的机会，还将在加拿大培养超快科学方面的高素质人才。